Transmission apparatus and method for controlling the transmission apparatus

ABSTRACT

A transmission apparatus includes: a data signal processor to add first data of a control signal to a data signal received, and transmit the data signal; a first signal output module to output second data of the control signal; an update controller to control an update of a function included in the first signal output module; and a second signal output module, when receiving a notice of an instruction for updating the function from the update controller, to output the first data that is the second data held therein when the notice thereof is received, wherein the second signal output module, when receiving a notice of a completion for updating the function from the update controller, outputs the first data that is the second data received from the first signal output module updated by the update controller.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2010-188772, filed on Aug. 25,2010, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a transmission apparatusand a method for controlling the transmission apparatus.

BACKGROUND

In a current optical core network, an optical transmission standardcalled “Optical Transport Network (OTN)” is widely used as a baseplatform. In OTN, data is transmitted using Synchronous Optical Network(SONET) or Synchronous Digital Hierarchy (SDH), which is a standard fora digital synchronous transmission method used for an existing telephoneservice and the like.

A transmission apparatus having a transmission method in which SONET orSDH is used, transmits a synchronous multiplexed signal that an overheadsignal (OH) is added to a multiplexed data signal. The OH is a signalfor performing monitoring, maintenance, and operation of thetransmission apparatus and a communication network. The synchronousmultiplexed signal may be referred to as a “frame” as a unit thereofhereinafter. By adding overhead data to a frame, the reliability of datatransmission can be improved.

By having appropriate information in a processing module that providesoverhead function, it is possible to realize monitoring, maintenance,and operation according to demands in the operation management of datatransmission. For example, a signal fail (SF) and signal degradation(SD) on a receiver of the transmission apparatus are detected asfailure. By adding Automatic Protection System (APS) bytes (K1 and K2bytes) in which such information (SF and SD) has been had to a frame,another transmission apparatus is notified of information regarding thetransmission apparatus in order to perform switching control. Inaddition, by adding J0 byte having a section tracing function to aframe, it is possible to monitor connection of paths. Since the usage ofoverhead is different between users, it is necessary to change aspecification of the overhead function different in each user. The“overhead function” herein refers to a function realized by transferringoverhead, and the “specification change of the overhead function” hereinrefers to, for example, a specification change of data included inoverhead.

Technologies used for a specification change of the overhead function asdescribed below have been proposed. One of the technologies is atechnology in which a specification of the overhead function is changedby upgrading firmware so as to change a setting value of a processingmodule that performs setting of a data signal. In addition, anothertechnology has been proposed in which a processing module that providesthe overhead function is configured by a Field-Programmable Gate Array(FPGA) that can be overwritten. In this technology, when a specificationchange of the overhead function needs to be performed, the FPGA isoverwritten, and then reconfiguration is performed to change thespecification of a processing module that provides the overheadfunction. Furthermore, another technology has been proposed in which anFPGA that configures the processing module that provides the overheadfunction is duplicated. In this case, when one of the FPGAs is subjectedto a specification change, the other FPGA is selected and used toperform processing, and then the FPGA that has been subjected to thespecification change is selected and used to perform processing (Forexample, refer to Japanese Laid-open Patent Publication No. 2005-80037).

SUMMARY

According to an aspect of the embodiment, there is provided atransmission apparatus including: a data signal processor to add firstdata of a control signal to a data signal received, and transmit thedata signal to other transmission apparatus; a first signal outputmodule to output second data of the control signal; an update controllerto control an update of a function included in the first signal outputmodule; and a second signal output module, when a notice of aninstruction for updating the function included in the first signaloutput module from the update controller is received, to output thefirst data of the control signal that is the second data of the controlsignal held in the second signal output module when the notice of theupdate instruction is received, wherein the second signal output module,when a notice of a completion for updating the function included in thefirst signal output module from the update controller is received,outputs the first data of the control signal that is the second data ofthe control signal received from the first signal output module updatedby the update controller.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a transmission apparatus according to afirst embodiment;

FIG. 2 is a block diagram illustrating the entirety of the transmissionapparatus;

FIG. 3 is a flowchart illustrating a process for updating thespecifications of overhead in the transmission apparatus according tothe first embodiment;

FIG. 4 is a block diagram of a transmission apparatus according to amodification of the first embodiment;

FIG. 5 is a block diagram of a transmission apparatus according to asecond embodiment;

FIG. 6 is a flowchart illustrating a process for updating thespecifications of overhead in the transmission apparatus according tothe second embodiment;

FIG. 7 is a block diagram of a transmission apparatus according to amodification of the second embodiment;

FIG. 8 is a block diagram of a transmission apparatus according to athird embodiment;

FIG. 9 is a flowchart illustrating a process for updating thespecifications of overhead in the transmission apparatus according tothe third embodiment; and

FIG. 10 is a block diagram of a transmission apparatus according to amodification of the third embodiment.

DESCRIPTION OF EMBODIMENTS

In a specification change performed by upgrading firmware, because anupdate is performed for each frame at intervals of 125 μs, there is atime lag in execution of a specification change.

On the other hand, if a processing module that provides the overheadfunction is configured by an FPGA, as in the related art example, thetime lag in execution of a specification change can be reduced. However,in this technology, the transmission apparatus may not be able totransmit a data signal during reconfiguration of the FPGA and thereforethere is a problem in that fails of the data signal are caused.

In addition, in the configuration in which the FPGA that configures aprocessing module that provides the overhead function is duplicated, itis possible to perform a specification change of the overhead functionwithout causing fails of the data signal. However, in this technology,since two FPGA having the same configuration need to be provided, costsare high and the size of circuits is large, leading to an inefficientconfiguration in terms of costs and actual installation.

Embodiments of a transmission apparatus and a method for controlling thetransmission apparatus disclosed herein will be described hereinafter indetail on the basis of the drawings. It is to be understood that thefollowing embodiments do not limit the transmission apparatus and themethod for controlling the transmission apparatus disclosed herein.

FIG. 1 is a block diagram of a transmission apparatus according to afirst embodiment. FIG. 2 is a block diagram illustrating the entirety ofthe transmission apparatus. FIG. 1 illustrates an interface (IF), whichis a part of the transmission apparatus illustrated in FIG. 2. In thetransmission apparatus according to this embodiment, each overheadfunction to be subjected to a specification change is a function ofadding a fixed value to a data signal as the overhead data. That is, inthe transmission apparatus according to this embodiment, the overheadfunction to be subjected to a specification change is a function ofadding static overhead data to an input data signal. In this case, evenif, for example, incorrect data is inserted into a part of overheadsubjected to a specification change, only a function such as aredundancy alarm is executed. Therefore, even if dummy data is simplyadded to a part of overhead to be subjected to a specification change,there is no problem. More specifically, this includes a case in whichdata to be added to J0 byte is changed, and, for example, a case inwhich the data to be added is changed from 64-bit data to 128-bit data.The overhead is an example of a “control signal”.

As illustrated in FIG. 1, the transmission apparatus according to thisembodiment has a data signal processor 3, a first FPGA 1, a second FPGA2, and a flash read-only memory (ROM) 4. The flash ROM 4 may be referredto as an “FPGA configuration flash ROM”. As illustrated in FIG. 2, thesecomponents are included in an IF 100 of the transmission apparatus.

Furthermore, as illustrated in FIG. 2, the transmission apparatusaccording to this embodiment has the IF 100 and a monitoring controller300. The transmission apparatus according to this embodiment is coupledto an operation terminal 400.

The data signal processor 3 is materialized with an application-specificintegrated circuit (ASIC). The data signal processor 3 receives a datasignal from an external apparatus (hereinafter referred to as “the otherapparatus”) that transmits and receives data to and from thetransmission apparatus. Here, the data signal is data according toSONET/SDH. Since a SONET/SDH frame complies with an InternationalTelecommunication Union (ITU) recommendation, detailed description ofthe SONET/SDH frame is omitted.

The data signal processor 3 performs processes such asparallel-to-serial conversion and serial-to-parallel conversion for datasignal serial output and serial input, and also performs determinationof routing paths. In addition, the data signal processor 3 outputsinformation used to process overhead, such as the number of errors andthe content of errors included in received data signals, to the firstFPGA 1, which will be described later. In addition, the data signalprocessor 3 receives, from the first FPGA 1, overhead data to be addedto a data signal. The data signal processor 3 then adds the overheaddata received from the first FPGA 1 to the data signal. Furthermore, thedata signal processor 3 makes the setting of the data signal usingsetting information of the data signal received from the first FPGA 1.The data signal processor 3 then outputs to the other apparatus the datasignal to which overhead data has been added. The data signal processor3 is an example of a “data signal processor”.

The first FPGA 1 has a data signal IF module 11, a data signal settingmodule 12, fixed OH function modules 13, and first OH function modules14. Here, the first FPGA 1 has a fixed OH function module 13 perspecification of overhead, that is, one module for each overheadfunction. In this embodiment, the first FPGA 1 has z fixed OH functionmodules 13. In addition, the first FPGA 1 has one first OH functionmodule 14 for each specification of the overhead. In this embodiment,the first FPGA 1 has m first OH function modules 14. A case in which anyof the m specifications of overhead is updated will be describedhereinafter. One of the first OH function modules 14 that has thespecification of the overhead to be updated will be simply referred toas the first OH function module 14.

The data signal IF module 11 is an interface for communication of databetween the data signal processor 3 and the first FPGA 1. The datasignal IF module 11 receives a data signal output from the data signalprocessor 3. In addition, the data signal IF module 11 outputs overheadoutput from the fixed OH function module 13 and the first OH functionmodule 14 and setting information of a data signal output from the datasignal setting module 12 to the data signal processor 3.

The data signal setting module 12 outputs setting information of a datasignal regarding the setting of clocks and the setting of reset timingof the data signal and the like.

The overhead functions controlled by the fixed OH function modules 13are functions that are not to be subjected to a specification change.One fixed OH function module 13 is provided for each overhead function.That is, there are the same number (z in this embodiment) of fixed OHfunction modules 13 as the number of overhead functions that are not tobe subjected to a specification change.

The fixed OH function modules 13 receive data used to process overhead,such as the number of errors and the content of errors included in datasignals, from the data signal IF module 11. The fixed OH functionmodules 13 then select overhead data corresponding to the content oferrors and the number of errors that have been input thereto, and outputthe selected overhead data to the data signal IF module 11. Here, the zfixed OH function modules 13 each output overhead data individually.Each of the fixed OH function modules 13 is an example of a “fixedsignal output module”.

The first OH function modules 14 perform a process for outputtingoverhead data having a fixed value to a data signal regardless of thecontent of the data signal. In other words, the first OH functionmodules 14 statically output the overhead data. One first OH functionmodule 14 is provided for each overhead function. That is, there are thesame number (m in this embodiment) of first OH function modules 14 asthe number of overhead functions that might be subjected to aspecification change.

The first OH function modules 14 receive a notice, from a centralprocessor (CPU) 5, that a second OH function module 20, which will bedescribed later, will be updated. In addition, the first OH functionmodules 14 receive a notice, from the CPU 5, that the update of thesecond OH function module 20 has been completed.

The first OH function modules 14 each have a selection module 141, aprevious value data buffer 142, and an update flag register module 143.Each of the first OH function modules 14 is an example of a “secondsignal output module”.

When the second OH function module 20 has been selected as the source ofoverhead data, the selection module 141 switches the source of overheaddata to the previous value data buffer 142 upon receiving a switchinginstruction from the update flag register module 143. The selectionmodule 141 then outputs overhead data received from the previous valuedata buffer 142 to the data signal IF module 11. At this time, theselection module 141 prevents data input from the second OH functionmodule 20 from overwriting the overhead.

In addition, when the previous value data buffer 142 has been selectedas the source of overhead data, the selection module 141 switches thesource of overhead data to a second OH function module 20 upon receivingan switching instruction from the update flag register module 143. Theselection module 141 then receives overhead data from the second OHfunction module 20 and outputs the overhead data to the data signal IFmodule 11.

In the normal operation, the previous value data buffer 142 overwritesoverhead data held thereby with overhead data output from a second OHfunction module 20.

When an update of a second OH function module 20 is performed, theprevious value data buffer 142 prevents overhead data output from thesecond OH function module 20 from overwriting overhead data storedtherein upon receiving an instruction for preventing overwriting fromthe update flag register module 143. That is, the previous value databuffer 142 keeps holding the overhead data stored therein. The previousvalue data buffer 142 then outputs the overhead data held thereby to theselection module 141.

Furthermore, when the update of the second OH function module 20 hasbeen completed, the previous value data buffer 142 resumes overwritingthe overhead data stored therein with overhead data output from thesecond OH function module 20 upon receiving an instruction for resumingoverwriting from the update flag register module 143.

In the normal operation, the update flag register module 143 instructsthe previous value data buffer 142 to perform overwriting overhead dataoutput from a second OH function module 20 until receiving a notice thatan update of the second OH function module 20 will be performed.Furthermore, in the normal operation, the update flag register module143 instructs the selection module 141 to select the overhead dataoutput from the second OH function module 20 until receiving a noticethat an update of the second OH function module 20 will be performed.This setting state of the update flag register module 143 may bereferred to as the “through setting”.

Upon receiving the notice that an update of the second OH functionmodule 20 will be performed, the update flag register module 143instructs the previous value data buffer 142 to prevent performingoverwriting the overhead data output from the second OH function module20. Furthermore, upon receiving the notice that an update of the secondOH function module 20 will be performed, the update flag register module143 instructs the selection module 141 to select the overhead dataoutput from the previous value data buffer 142. This setting state ofthe update flag register module 143 may be referred to as the “holdsetting”.

Upon receiving a notice that the update of the second OH function module20 has been completed, the update flag register module 143 instructs theprevious value data buffer 142 to perform overwriting the overhead dataoutput from the second OH function module 20. In addition, uponreceiving the notice that the update of the second OH function module 20has been completed, the update flag register module 143 instructs theselection module 141 to select the overhead data output from the secondOH function module 20. That is, upon receiving the notice that an updateof the second OH function module 20 has been completed, the update flagregister module 143 returns to the through setting, which is a normaloperation state.

The second FPGA 2 has second OH function modules 20. In addition, thesecond OH function modules 20 each have a static OH processing module201.

The second OH function modules 20 have a function of providing overheaddata to be added to a data signal by the first OH function modules 14.Second OH function modules 20 are provided corresponding to the first OHfunction modules 14 on one-to-one basis. The number of second OHfunction modules 20 may be larger than or equal to that of the first OHfunction modules 14. In this embodiment, the number of second OHfunction modules 20 is y (y≧m).

The static OH processing modules 201 have overhead data whosespecifications correspond to the process performed by the first OHfunction modules 14. The specifications of overhead included in thestatic OH processing modules 201 are ones that might be changed. Inaddition, each static OH processing module 201 has one overhead datablock. Each of the static OH processing modules 201 is an example of an“information storage module”.

Since the second OH function modules 20 output overhead data included inthe static OH processing modules 201 included therein to the first OHfunction modules 14, the second OH function modules 20 invariablyprovide the first OH function modules 14 with the same overhead data. Inother words, each second OH function module 20 statically provides eachfirst OH function module 14 with overhead data.

If an update of a second OH function module 20 is performed, the CPU 5reconfigures the second FPGA 2 using configuration data, which is storedin the flash ROM 4, for changing the specifications of overhead of thestatic OH processing module 201 to new specifications. Morespecifically, an FPGA configuration controller 101 reconfigures thesecond FPGA 2 upon receiving an instruction from the CPU 5. Thus, thesecond OH function module 20 is upgraded. Furthermore, the CPU 5performs initial setting of all the y static OH processing modules 201using overhead setting data held by a backup memory 103. Each of thesecond OH function modules 20 is an example of a “first signal outputmodule”. The overhead data output from each second OH function module 20is an example of “information regarding a first control signal”.

The flash ROM 4 stores configuration data of the second FPGA 2 forchanging the specifications of overhead input by an operator using theoperation terminal 400 to new specifications.

The monitoring controller 300 receives error information or the likefrom IFs 100. The monitoring controller 300 then outputs the errorinformation or the like to the operation terminal 400 and notifies anoperator of the error information or the like. The operator refers tothe error information or the like and inputs overhead setting data anddata signal setting data using the operation terminal 400.

The monitoring controller 300 has a backup memory 301. The monitoringcontroller 300 receives overhead setting data and data signal settingdata input by an operator using the operation terminal 400 and storesthe data in the backup memory 301. The monitoring controller 300 thenoutputs the overhead setting data and the data signal setting data tothe IF 100.

In addition, the monitoring controller 300 receives configuration data,which is input by the operator using the operation terminal 400, of thesecond FPGA 2 for changing the specifications of a second OH functionmodule 20 to new specifications. The monitoring controller 300 thenoutputs, to the IF 100, the received configuration data of the secondFPGA 2 for changing the specifications of the second OH function module20 to new specifications.

A monitoring control IF 102 is an interface for communicating databetween the monitoring controller 300 and an IF 100.

The FPGA configuration controller 101 configures the second FPGA 2 usingconfiguration data of the second FPGA 2 for changing the specificationsof a second OH function module 20 stored in the flash ROM 4 to newspecifications upon receiving an instruction from the CPU 5. The FPGAconfiguration controller 101 also configures the first FPGA 1 in thesame manner.

The CPU 5 stores, in the backup memory 103, data signal setting data andoverhead setting data input from the monitoring controller 300. Inaddition, the CPU 5 makes the setting of the data signal processor 3using data signal setting data stored in the backup memory 103. Inaddition, the CPU 5 makes the setting of a second OH function module 20using overhead setting data stored in the backup memory 103. Here, sincethe data signal setting data and the overhead setting data are alsostored in the backup memory 301 of the monitoring controller 300, thedata signal setting data and the overhead setting data may notnecessarily be stored in the backup memory 103. In that case, the CPU 5reads the data signal setting data or the overhead setting data from thebackup memory 301 to make the setting of the data signal processor 3 orthe second FPGA 2.

In addition, the CPU 5 controls the update of the second FPGA 2. Forexample, the CPU 5 issues a command for executing an update of thesecond FPGA 2 to the FPGA configuration controller 101 and notifies thefirst OH function module 14 of the update of the second FPGA 2. The CPU5 is an example of an “update controller”.

Next, the flow of a process for updating the specifications of overheadin the transmission apparatus according to this embodiment will bedescribed with reference to FIG. 3. FIG. 3 is a flowchart illustratingthe process for updating the specifications of overhead in thetransmission apparatus according to the first embodiment.

A first OH function module 14 outputs overhead data received from asecond OH function module 20 to the data signal processor 3 (operationS101).

The data signal processor 3 adds the overhead data output from the fixedOH function modules 13 and the first OH function modules 14 to a datasignal and transmits the resultant data signal to the other apparatus(operation S102).

The previous value data buffer 142 overwrites overhead data storedtherein with the overhead data received from the second OH functionmodule 20 (operation S103).

The CPU 5 determines whether or not the CPU 5 has received aninstruction for updating the specifications of overhead of the second OHfunction module 20 from the operation terminal 400 (operation S104). Ifthe CPU 5 has not received an instruction for updating thespecifications of overhead (NO in operation S104), the process returnsto operation S101.

On the other hand, if the CPU 5 has received an instruction for updatingthe specifications of overhead (YES in S104), the CPU 5 writesconfiguration data having new specifications to the flash ROM 4(operation S105).

The update flag register module 143 changes the setting to the holdsetting (operation S106). In this case, overwriting of overhead data isprevented in the previous value data buffer 142, and the selectionmodule 141 is instructed to select overhead data output from theprevious value data buffer 142.

The CPU 5 determines whether or not the processing in operation S106 hasbeen completed for all the m first OH function modules 14 (operationS107). If there is any first OH function module 14 for which theprocessing has not been completed (NO in operation S107), the processreturns to operation S106.

On the other hand, if the processing has been completed for all thefirst OH function modules 14 (YES in operation S107), the first OHfunction modules 14 output overhead data received from the previousvalue data buffer 142 to the data signal processor 3 (operation S108).

The data signal processor 3 adds overhead data output from the fixed OHfunction modules 13 and the first OH function modules 14 to a datasignal and transmits the resultant data signal to the other apparatus(operation S109).

The FPGA configuration controller 101 reconfigures the second FPGA 2using data stored in the flash ROM 4 (operation 5110).

The CPU 5 performs initial setting of the second FPGA 2 using overheadsetting data stored in the backup memory 103 (operation S111).

The update flag register module 143 changes the setting to the throughsetting (operation S112).

The selection module 141 outputs overhead data obtained from the staticOH processing module 201 to the data signal processor 3 (operationS113).

The data signal processor 3 adds overhead data output from the fixed OHfunction modules 13 and the first OH function modules 14 to a datasignal and transmits the resultant data signal to the other apparatus(operation S114).

Here, for convenience of description, the update of the second FPGA 2 inoperations 5110 and S111 is performed after the addition of data outputfrom the previous value data buffer 142 and the transmission of a datasignal in operations S108 and S109 in the flowchart of FIG. 3. However,in practice, operations S108 and S109 are still being executed whileoperations 5110 and S111 are being performed.

As described above, the transmission apparatus according to the firstembodiment performs a process for statically adding overhead data to adata signal. While the specifications of the overhead are being updated,overhead data immediately before the update is added to the data signaland the resultant data signal is transmitted to the other apparatus. Indoing so, it is possible to avoid causing a data signal fail even whilethe specifications of overhead are being updated. That is, it ispossible to execute a specification change of processing of overheadwithout causing a data signal fail.

In addition, the size of circuits in an overhead processing module inthe transmission apparatus according to this embodiment isadvantageously the same as that of circuits for performing normalprocessing of overhead, except for an increase due to the previous valuedata buffer 142. Therefore, the size of circuits in the overheadprocessing module according to this embodiment can be restricted toapproximately half that of circuits in a transmission apparatus in whichoverhead processing modules are fully duplicated, as well as fabricationcosts being reduced.

FIG. 4 is a block diagram of a transmission apparatus according to amodification of the first embodiment. This modification is differentfrom the embodiment in that an FPGA capable of performing partialconfiguration is used therein.

Because the FPGA capable of performing partial configuration is used asthe first FPGA 1, the first FPGA 1 can have the function of the secondFPGA 2 according to the first embodiment.

The first OH function modules 14 each have the selection module 141, theprevious value data buffer 142, the update flag register module 143, anda static OH processing module 144. Here, the static OH processing module144 has the function of the static OH processing module 201 according tothe first embodiment.

When the static OH processing module 144 has been selected as the sourceof overhead data, the selection module 141 switches the source ofoverhead data to the previous value data buffer 142 upon receiving aswitching instruction from the update flag register module 143. Theselection module 141 then outputs overhead data received from theprevious value data buffer 142 to the data signal IF module 11. At thistime, the selection module 141 prevents data input from the static OHprocessing module 144 from overwriting a data signal.

In addition, when the previous value data buffer 142 has been selectedas the source of overhead data, the selection module 141 switches thesource of overhead data to the static OH processing module 144 uponreceiving an switching instruction from the update flag register module143. The selection module 141 then receives overhead data from thestatic OH processing module 144 and outputs the overhead data receivedfrom the static OH processing module 144 to the data signal IF module11.

In the normal operation, the previous value data buffer 142 overwritesoverhead data stored therein with overhead data output from the staticOH processing module 144.

When an update of the static OH processing module 144 is performed, theprevious value data buffer 142 prevents overhead data output from thestatic OH processing module 144 from overwriting overhead data storedtherein upon receiving an instruction for preventing overwriting fromthe update flag register module 143. That is, the previous value databuffer 142 keeps holding the overhead data stored therein. The previousvalue data buffer 142 then outputs the overhead data held thereby to theselection module 141.

Furthermore, when an update of the static OH processing module 144 hasbeen completed, the previous value data buffer 142 resumes overwritingthe overhead data stored therein with overhead data output from thestatic OH processing module 144 upon receiving an instruction forresuming overwriting from the update flag register module 143.

In the normal operation, the update flag register module 143 instructsthe previous value data buffer 142 to perform overwriting the overheaddata output from the static OH processing module 144 until receiving anotice that an update of the static OH processing module 144 will beperformed. Furthermore, in the normal operation, the update flagregister module 143 instructs the selection module 141 to select theoverhead data output from the static OH processing module 144 untilreceiving a notice that an update of the static OH processing module 144will be performed.

Upon receiving a notice that an update of the static OH processingmodule 144 will be performed, the update flag register module 143instructs the previous value data buffer 142 to prevent performingoverwriting the overhead data output from the static OH processingmodule 144. Furthermore, upon receiving the notice that the update ofthe static OH processing module 144 will be performed, the update flagregister module 143 instructs the selection module 141 to select theoverhead data output from the previous value data buffer 142.

Upon receiving a notice that the update of the static OH processingmodule 144 has been completed, the update flag register module 143instructs the previous value data buffer 142 to perform overwriting theoverhead data output from the static OH processing module 144. Inaddition, upon receiving the notice that the update of the static OHprocessing module 144 has been completed, the update flag registermodule 143 instructs the selection module 141 to select the overheaddata output from the static OH processing module 144.

Since the first FPGA 1 can perform the partial configuration, it ispossible to update only the static OH processing module 144. Thereconfiguration of the static OH processing module 144 is performed bythe FPGA configuration controller 101 using configuration data, which isstored in the flash ROM 4, for changing the specifications of overheadof the static OH processing module 144 to new specifications.Furthermore, the CPU 5 performs initial setting of the static OHprocessing module 144 using overhead setting data held by the backupmemory 103.

As described above, in the transmission apparatus according to thismodification, it is possible to execute a specification change ofprocessing of overhead without causing a data signal fail. Since thepartial configuration is performed, it is also possible to suppressadverse effects on other overhead function modules that do not need aspecification change.

FIG. 5 is a block diagram of a transmission apparatus according to asecond embodiment. The transmission apparatus according to thisembodiment is different from that according to the first embodiment inthat overhead data that is suitable for a data signal is selected fromamong multiple overhead data blocks, and the selected overhead data isadded to the data signal. In other words, the transmission apparatusaccording to this embodiment dynamically changes overhead data to beadded to a data signal. More specifically, this includes a case in whicha function of switching a transmission path is included in informationof an overhead. The overall configuration of the transmission apparatusaccording to this embodiment is also represented by FIG. 2. In FIG. 5,components having the same reference numerals as in FIG. 1 have the samefunctions unless otherwise described.

The first FPGA 1 has the data signal IF module 11, the data signalsetting module 12, the fixed OH function modules 13, and third OHfunction modules 15.

In processing of overhead performed by the third OH function modules 15,overhead data that is suitable for the content of a data signal isoutput. One third OH function module 15 is provided for each overheadfunction. That is, there are the same number (n in this embodiment) ofthird OH function modules 15 as the number of overhead functions thatmight be subjected to a specification change.

A third OH function module 15 receives, from the CPU 5, a notice that afourth OH function module 21, which will be described later, will beupdated. In addition, the third OH function module 15 receives, from theCPU 5, a notice that an update of the fourth OH function module 21 hasbeen completed.

In addition, the third OH function modules 15 each have an alarmtermination module 151, a dynamic OH processing module 152, and aselection module 153. Each of the third OH function modules 15 is anexample of a “second signal output module”. Overhead data output by eachof the third OH function modules 15 is an example of “data of controlsignal”.

The alarm termination module 151 detects an alarm from a data signalincluded in the data signal IF module 11 and terminates the detectedalarms. The alarm termination module 151 then outputs the content of thedetected alarm to the dynamic OH processing module 152.

The dynamic OH processing module 152 stores multiple overhead datablocks. The dynamic OH processing module 152 also stores data of thecorrespondence relation between the content of alarms and the multipleoverhead data blocks in advance.

Furthermore, if an update of a fourth OH function module 21 is performedin a state in which the selection module 153, which will be describedlater, has selected a dynamic OH processing module 212, the dynamic OHprocessing module 152 receives, from the CPU 5, an instruction forchanging the correspondence relation between the content of alarms andthe multiple overhead data blocks. The dynamic OH processing module 152then, immediately before the update, changes the correspondence relationbetween the content of alarms and the multiple overhead data blocks inaccordance with a process for selecting overhead performed by the fourthOH function module 21, and stores data of the new correspondencerelation. For example, in the case of a process for selecting atransmission path in accordance with the content of alarms, the dynamicOH processing module 152 determines which transmission path is selectedwhen a certain content of alarm has been received, and stores data ofthe correspondence relation between overhead data blocks for selectingtransmission paths corresponding to alarms and the content of alarms.

On the other hand, if an update of a fourth OH function module 21 isperformed in a state in which the selection module 153 has selected thedynamic OH processing module 152, the dynamic OH processing module 152keeps performing a process that is currently being performed.

The dynamic OH processing module 152 receives the content of an alarmdetected by the alarm termination module 151. The dynamic OH processingmodule 152 then extracts overhead data corresponding to the content ofthe received alarm. The dynamic OH processing module 152 then outputsthe extracted overhead data to the selection module 153.

The selection module 153 receives, from the CPU 5, an instruction forselecting either the dynamic OH processing module 152 or the dynamic OHprocessing module 212. The selection module 153 then obtains overheaddata output from the selected dynamic OH processing module and outputsthe obtained overhead data to the data signal IF module 11.

Now, the selection of either the dynamic OH processing module 152 or thedynamic OH processing module 212 performed by the selection module 153will be specifically described. First, when the transmission apparatusis activated, the selection module 153 selects either the dynamic OHprocessing module 152 or the dynamic OH processing module 212 inaccordance with the specifications of a data signal.

After that, if an update of a fourth OH function module 21 is performedin a state in which the dynamic OH processing module 152 has beenselected, the selection module 153 keeps selecting the dynamic OHprocessing module 152. When the update of the fourth OH function module21 has been completed, the selection module 153 switches the selectionto the dynamic OH processing module 212.

On the other hand, if an update of a fourth OH function module 21 isperformed in a state in which the dynamic OH processing module 212 hasbeen selected, the selection module 153 switches the selection to thedynamic OH processing module 152. When the update of the fourth OHfunction module 21 has been completed, the selection module 153 switchesthe selection to the dynamic OH processing module 212.

In the second FPGA 2, when all the n third OH function modules 15 outputoverhead data output from the dynamic OH processing modules 152 to thedata signal IF module 11, only a region necessary to form the fourth OHfunction module 21 is provided and therefore there is no fourth OHfunction module 21. In the second FPGA 2, a region is provided whosesize is such that a number of fourth OH function modules 21 that areexpected to be updated in relation to the n third OH function modules 15can be included therein. In this embodiment, x fourth OH functionmodules 21 are provided.

In a state in which the third OH function modules 15 are provided withoverhead data from the fourth OH function modules 21, the second FPGA 2has a number of fourth OH function modules 21 that are used by the thirdOH function modules 15. The fourth OH function modules 21 each have analarm termination module 211 and the dynamic OH processing module 212.

That is, a fourth OH function module 21 is formed on the second FPGA 2if a specification change of overhead is performed in a state in which athird OH function module 15 outputs overhead data output from thedynamic OH processing module 152 to the data signal IF module 11. Inaddition, a fourth OH function module 21 formed on the second FPGA 2 canbe updated. Each of the fourth OH function modules 21 is an example of a“first signal output module”.

The alarm termination module 211 detects an alarm from a data signalincluded in the data signal IF module 11 and terminates the detectedalarm. The alarm termination module 211 then outputs the content of thedetected alarm to the dynamic OH processing module 212.

The dynamic OH processing module 212 holds overhead data whosespecifications correspond to a process performed by the third OHfunction modules 15. The specifications of overhead included in thedynamic OH processing module 212 are ones that might be changed. Thedynamic OH processing module 212 has multiple overhead data blocks. Thedynamic OH processing module 212 stores in advance the correspondencerelation between contents of alarms detected by the alarm terminationmodule 211 and the multiple overhead data blocks stored therein.

The dynamic OH processing module 212 obtains, from among the multipleoverhead data blocks included therein, overhead data corresponding to acontent of an alarm detected by the alarm termination module 211.

A fourth OH function module 21 outputs the overhead data obtained by thedynamic OH processing module 212 to a third OH function module 15. Inother words, each of the fourth OH function modules 21 dynamicallychanges overhead data and provides each of the third OH function modules15 with the changed overhead data.

If an update of a fourth OH function module 21 is performed, the FPGAconfiguration controller 101 reconfigures the second FPGA 2 usingconfiguration data, which is stored in the flash ROM 4, for changing thespecifications of overhead of the dynamic OH processing module 212 tonew specifications. Thus, the fourth OH function module 21 is upgraded.Furthermore, the CPU 5 performs initial setting of all the x dynamic OHprocessing modules 212 using overhead setting data held by a backupmemory 103.

Next, the flow of a process for updating the specifications of overheadin the transmission apparatus according to this embodiment will bedescribed with reference to FIG. 6. FIG. 6 is a flowchart illustratingthe process for updating the specifications of overhead in thetransmission apparatus according to the second embodiment.

The selection module 153 selects either the dynamic OH processing module152 or the dynamic OH processing module 212 in accordance with thespecifications of a data signal and outputs overhead data of theselected module to the data signal IF module 11 (operation S201).

The data signal processor 3 adds the overhead data output from the fixedOH function modules 13 and the third OH function modules 15 to the datasignal and transmits the resultant data signal to the other apparatus(operation S202).

The CPU 5 determines whether or not the CPU 5 has received, from theoperation terminal 400, an instruction for changing the specificationsof overhead (operation S203). If the CPU 5 has not received aninstruction for changing the specifications of overhead (NO in operationS203), the process returns to operation S201.

On the other hand, if the CPU 5 has received an instruction for changingthe specifications of overhead (YES in S203), the CPU 5 determineswhether or not the source of overhead data added to the data signal isthe dynamic OH processing module 212 (operation S204).

If the source of overhead data is the dynamic OH processing module 212(YES in operation S204), the CPU 5 writes configuration data for newspecifications to the flash ROM 4 (operations S205).

The dynamic OH processing module 152 changes the setting for processingoverhead data, such as selection of data, in accordance with the settingof the dynamic OH processing module 212 (operation S206).

The selection module 153 switches the selection to the dynamic OHprocessing module 152 and obtains overhead data output from the dynamicOH processing module 152 (operation S207).

The CPU 5 determines whether or not the processing in operations S205 toS207 has been completed for all the n third OH function modules 15(operation S208). If there is any third OH function module 15 for whichthe processing has not been completed (NO in operation S208), theprocess returns to operation S206.

On the other hand, if the processing has been completed for all thethird OH function modules 15 (YES in operation S208) or if the source ofoverhead data is the dynamic OH processing module 152 (NO in operationS204), the selection module 153 outputs overhead data received from thedynamic OH processing module 152 to the data signal IF module 11(operation S209).

The data signal processor 3 adds overhead data output from the fixed OHfunction modules 13 and the third OH function modules 15 to a datasignal and transmits the resultant data signal to the other apparatus(operation S210).

The FPGA configuration controller 101 reconfigures the second FPGA 2using data stored in the flash ROM 4 (operation S211).

The CPU 5 performs initial setting of the second FPGA 2 using overheadsetting data stored in the backup memory 103 (operation S212).

The selection module 153 switches the selection to the dynamic OHprocessing module 212 and obtains overhead data output from the dynamicOH processing module 212 (operation S213).

The selection module 153 outputs the overhead data obtained from thedynamic OH processing module 212 to the data signal IF module 11(operation S214).

The data signal processor 3 adds overhead data output from the fixed OHfunction modules 13 and the third OH function modules 15 to a datasignal and transmits the resultant data signal to the other apparatus(operation S215).

Here, for convenience of description, the update of the second FPGA 2 inoperations S211 and S212 is performed after the addition of data outputfrom the dynamic OH processing module 152 and the transmission of a datasignal in operations S209 and S210 in the flowchart of FIG. 6. However,in practice, operations S209 and S210 are still being executed whileoperations S211 and S212 are being performed.

As described above, the transmission apparatus according to the secondembodiment dynamically changes overhead data in accordance with thespecifications of a data signal and adds the overhead data to the datasignal. While the specifications of overhead are being updated, thetransmission apparatus according to the second embodiment adds overheadthat has been subjected to a process corresponding to a processimmediately before the update to the data signal and transmits theresultant data signal to the other apparatus. In doing so, it ispossible to avoid causing a data signal fail even while thespecifications of overhead are being updated. That is, it is possible toexecute a specification change of processing of overhead without causinga data signal fail even when overhead data is dynamically changed inaccordance with the specifications of a data signal and added to thedata signal.

In addition, the size of circuits in all the overhead processing modulesin the transmission apparatus according to this embodiment is oneobtained by adding the number (x in this embodiment) of overheadprocessing modules that are expected to be changed in the future tocircuits for performing normal processing of overhead. Therefore, thesize of circuits in the overhead processing module according to thisembodiment can be restricted to be smaller than that of circuits in atransmission apparatus in which overhead processing modules are fullyduplicated, as well as fabrication costs being reduced.

FIG. 7 is a block diagram of a transmission apparatus according to amodification of the second embodiment. This modification is differentfrom the second embodiment in that an FPGA capable of performing partialconfiguration is used therein.

Because the FPGA capable of performing partial configuration is used asthe first FPGA 1, the first FPGA 1 can have the function of the secondFPGA 2 according to the second embodiment.

The third OH function module 15 has the alarm termination module 151,the dynamic OH processing module 152, the selection module 153, and apartial OH function module 154. The partial OH function module 154 hasan alarm termination module 155 and a dynamic OH processing module 156.Here, the partial OH function module 154 has the function of fourth OHfunction module 21 in the second FPGA 2 according to the secondembodiment.

The alarm termination module 151 detects an alarm from a data signalincluded in the data signal IF module 11 and terminates the detectedalarm. The alarm termination module 151 then outputs the content of thedetected alarm to the dynamic OH processing module 152.

The dynamic OH processing module 152 stores multiple overhead datablocks. The dynamic OH processing module 152 also stores data of thecorrespondence relation between the content of alarms and the multipleoverhead data blocks in advance.

Furthermore, if an update of the partial OH function module 154 isperformed in a state in which the selection module 153 has selected thedynamic OH processing module 156, the dynamic OH processing module 152receives, from the CPU 5, an instruction for changing the correspondencerelation between the content of alarms and the multiple overhead datablocks. The dynamic OH processing module 152 then changes thecorrespondence relation between the content of alarms and the multipleoverhead data blocks in accordance with a process such as selection ofoverhead data performed by the dynamic OH processing module 156immediately before the update, and stores data of the new correspondencerelation.

On the other hand, if an update of the partial OH function module 154 isperformed in a state in which the selection module 153 has selected thedynamic OH processing module 152, the dynamic OH processing module 152keeps performing a process that is currently being performed.

The dynamic OH processing module 152 receives the content of an alarmdetected by the alarm termination module 151. The dynamic OH processingmodule 152 then extracts overhead data corresponding to the content ofthe received alarm. The dynamic OH processing module 152 then outputsthe extracted overhead data to the selection module 153.

The selection module 153 receives, from the CPU 5, an instruction forselecting either the dynamic OH processing module 152 or the dynamic OHprocessing module 156. The selection module 153 then obtains overheaddata output from the selected dynamic OH processing module and outputsthe obtained overhead data to the data signal IF module 11.

Now, the selection of either the dynamic OH processing module 152 or thedynamic OH processing module 156 performed by the selection module 153will be specifically described. First, when the transmission apparatusis activated, the selection module 153 selects either the dynamic OHprocessing module 152 or the dynamic OH processing module 156 inaccordance with the specifications of a data signal.

After that, if an update of the partial OH function module 154 isperformed in a state in which the dynamic OH processing module 152 hasbeen selected, the selection module 153 keeps selecting the dynamic OHprocessing module 152. When the update of the partial OH function module154 has been completed, the selection module 153 switches the selectionto the dynamic OH processing module 156.

On the other hand, if an update of the partial OH function module 154 isperformed in a state in which the dynamic OH processing module 156 hasbeen selected, the selection module 153 switches the selection to thedynamic OH processing module 152. When the update of the partial OHfunction module 154 has been completed, the selection module 153switches the selection to the dynamic OH processing module 156.

The alarm termination module 155 detects an alarm from a data signalincluded in the data signal IF module 11 and terminates the detectedalarm. The alarm termination module 155 then outputs the content of thedetected alarm to the dynamic OH processing module 156.

The dynamic OH processing module 156 has multiple overhead data blocks.Furthermore, the dynamic OH processing module 156 stores in advance dataof the correspondence relation between the content of alarms detected bythe alarm termination module 155 and the multiple overhead data blocksstored therein.

The dynamic OH processing module 156 obtains, from among the multipleoverhead data blocks included therein, overhead data corresponding tothe content of an alarm detected by the alarm termination module 155.

The dynamic OH processing module 156 outputs the obtained overhead datato the selection module 153.

Since the first FPGA 1 can perform the partial configuration, it ispossible to update only the partial OH function module 154. If an updateof the partial OH function module 154 is performed, the reconfigurationof the partial OH function module 154 is performed by the FPGAconfiguration controller 101 using configuration data, which is storedin the flash ROM 4, for changing the specifications of overhead of thedynamic OH processing module 156 to new specifications. Thus, thespecifications of the dynamic OH processing module 156 are updated.Furthermore, the CPU 5 performs initial setting of the dynamic OHprocessing module 156 using overhead setting data held by the backupmemory 103.

As described above, in this modification, it is possible to execute aspecification change of processing of overhead using the partialconfiguration performed by an FPGA without causing a data signal faileven when overhead data is dynamically changed in accordance with thespecifications of a data signal and added to the data signal. The sizeof circuits in all the overhead processing modules according to thismodification can be restricted to that of circuits obtained by adding atleast one overhead processing module to circuits for performing normalprocessing of overhead. Therefore, the size of circuits can be furtherreduced.

FIG. 8 is a block diagram of a transmission apparatus according to athird embodiment. The transmission apparatus according to thisembodiment is different from that according to the first embodiment inthat a process for adding static overhead data to a data signal can bechanged to a process for dynamically changing overhead data to be addedto the data signal. The overall configuration of the transmissionapparatus according to this embodiment is also represented by FIG. 2. InFIG. 8, components having the same reference numerals as in FIG. 1 havethe same functions unless otherwise described.

In this embodiment also, the update of the overhead function of adding afixed value of overhead data and the update of the overhead function ofadding appropriate overhead data corresponding to the specifications ofa data signal are the same as in the first embodiment and the secondembodiment. However, regardless of updating a second OH function module20 or a fourth OH function module 21, both the second OH function module20 and the fourth OH function module 21 need to be stopped. Therefore,even if a second OH function module 20 is updated, each of the third OHfunction modules 15 needs to perform processing using the alarmtermination module 151 and the dynamic OH processing module 152 duringthe update as in the second embodiment. In addition, even if a fourth OHfunction module 21 is updated, each of the first OH function modules 14needs to perform processing using data of the previous value data buffer142 during the update as in the first embodiment.

Therefore, a case will be described hereinafter in which a state whereoverhead data that has been output from a second OH function module 20and obtained by a first OH function module 14 is added to a data signalis changed to a state where overhead data that is suitable for thespecifications of the data signal is selected and added to the datasignal. This includes, for example, a case in which OH byte, which hasnot been specified by the recommendation, is to be used.

As illustrated in FIG. 8, the first FPGA 1 has the data signal IF module11, the data signal setting module 12, the fixed OH function modules 13,the first OH function modules 14, the third OH function modules 15, andOH function selection modules 16.

The OH function selection modules 16 each have a selection module 161.

The selection module 161 selects, upon receiving an instruction from theCPU 5, either the selection module 141 in a first OH function module 14or the dynamic OH processing module 212 in a fourth OH function module21 as the source of overhead data to be added to a data signal.

An OH function selection module 16 outputs the overhead data obtainedfrom the module selected by the selection module 161 to the data signalIF module 11.

Now, the operation for selecting a function module performed by the OHfunction selection module 16 will be specifically described. In thisembodiment, since the initial state is a state in which overhead datathat has been output from a second OH function module 20 and obtained bythe first OH function module 14 is added to a data signal, the selectionmodule 161 is assumed to have selected the selection module 141 in thefirst OH function module 14 at first. The OH function selection module16 then receives, through the CPU 5, an instruction for changing from aprocess, which has been input by the operation terminal 400 and isperformed by the static OH processing module 201, of adding overheaddata having a fixed value to a process of selecting appropriate overheaddata that is suitable for a the specifications of a data signal andadding the overhead data to the data signal. Upon receiving the changeinstruction, the selection module 161 waits for completion of thesetting of the dynamic OH processing module 212 and then performsswitching, so that the dynamic OH processing module 212 is selected asthe source of overhead data.

Upon receiving an instruction for updating the overhead function fromthe CPU 5, the update flag register module 143 in the first OH functionmodule 14 changes the setting to the hold setting.

Upon receiving an instruction from the update flag register module 143,the previous value data buffer 142 in the first OH function module 14prevents overwriting overhead data held thereby. The previous value databuffer 142 then outputs the overhead data held thereby to the selectionmodule 141.

The selection module 141 in the first OH function module 14 has selectedand obtained overhead data output by the second OH function module 20 atfirst. The selection module 141 then outputs the overhead data output bythe second OH function module 20 to the OH function selection module 16.

After that, upon receiving an instruction from the update flag registermodule 143, the selection module 141 selects and obtains overhead dataoutput by the previous value data buffer 142. The selection module 141then outputs the overhead data output by the previous value data buffer142 to the OH function selection module 16.

This process of a first OH function module 14 is performed by all the mfirst OH function modules 14.

Upon receiving an instruction for updating the overhead function, thesecond FPGA 2 is reconfigured by the FPGA configuration controller 101using data stored in the flash ROM 4. In this case, configuration dataincluding new specifications of the second OH function module 20 isstored in the flash ROM 4. Thus, the second FPGA 2 is upgraded.

All the y second OH function modules 20 and all the x fourth OH functionmodules 21 are initialized using overhead setting data stored in thebackup memory 103.

When the initialization has been completed, the alarm termination module211 detects an alarm from a data signal included in the data signal IFmodule 11 and terminates the detected alarm. The alarm terminationmodule 211 then outputs the content of the detected alarm to the dynamicOH processing module 212.

The dynamic OH processing module 212 obtains, from among the multipleoverhead data blocks included therein, overhead data corresponding tothe content of the alarm detected by the alarm termination module 211.

The fourth OH function module 21 outputs the overhead data obtained bythe dynamic OH processing module 212 to the OH function selection module16.

Next, the flow of a process for updating the specifications of overheadin the transmission apparatus according to this embodiment will bedescribed with reference to FIG. 9. A case will be described in which astate where overhead data that has been output from a second OH functionmodule 20 and obtained by a first OH function module 14 is added to adata signal is changed to a state where overhead data that is suitablefor the specifications of the data signal is selected and added to thedata signal. FIG. 9 is a flowchart illustrating the process for updatingthe specifications of overhead in the transmission apparatus accordingto the third embodiment.

The selection module 141 selects the second OH function module 20, andthen obtains overhead data from the second OH function module 20 andoutputs the overhead data. The selection module 161 selects and obtainsoverhead data output from the first OH function module 14. An OHfunction selection module 16 outputs the overhead data obtained by theselection module 161 to the data signal IF module 11 (operation S301).

The data signal processor 3 adds overhead data input from the fixed OHfunction modules 13 and the OH function selection modules 16 to a datasignal and transmits the resultant data signal to the other apparatus(operation S302).

The CPU 5 determines whether or not the CPU 5 has received aninstruction for changing the specifications of overhead from theoperation terminal 400 (operation S303). If the CPU 5 has not receivedan instruction for changing the specifications of overhead (NO inoperation S303), the process returns to operation S301.

On the other hand, if the CPU 5 has received an instruction for changingthe specifications of overhead (YES in S303), the CPU 5 writesconfiguration data for new specifications to the flash ROM 4 (operationS304).

The update flag register module 143 changes the setting to the holdsetting (operation S305). In this case, overwriting of overhead data isprevented in the previous value data buffer 142, and the selectionmodule 141 is instructed to select overhead data output from theprevious value data buffer 142.

The CPU 5 determines whether or not the processing in operation S305 hasbeen completed for all the m first OH function modules 14 (operationS306). If there is any first OH function module 14 for which theprocessing has not been completed (NO in operation S306), the processreturns to operation S305.

On the other hand, if the processing has been completed for all thefirst OH function modules 14 (YES in operation S306), the selectionmodule 141 obtains overhead data output from the previous value databuffer 142. The first OH function module 14 outputs the overhead dataobtained by the selection module 141 to the selection module 161. The OHfunction selection module 16 outputs the overhead data obtained from theprevious value data buffer 142 that has been output from the first OHfunction module 14 and obtained by the selection module 161 to the datasignal IF module 11 (operation S307).

The data signal processor 3 adds overhead data output from the fixed OHfunction modules 13 and the OH function selection module 16 to a datasignal and transmits the resultant data signal to the other apparatus(operation S308).

The FPGA configuration controller 101 reconfigures the second FPGA 2using data stored in the flash ROM 4 (operation S309).

The CPU 5 performs initial setting of the second FPGA 2 using overheadsetting data stored in the backup memory 103 (operation S310).

The selection module 161 switches the selection to the dynamic OHprocessing module 212 and obtains overhead data from the dynamic OHprocessing module 212 (operation S311).

The OH function selection module 16 outputs the overhead data that hasbeen obtained by the selection module 161 from the dynamic OH processingmodule 212 to the data signal IF module 11 (operation S312).

The data signal processor 3 adds overhead data output from the fixed OHfunction modules 13 and the OH function selection module 16 to a datasignal and transmits the resultant data signal to the other apparatus(operation S313).

Here, for convenience of description, the update of the second FPGA 2 inoperations S309 and S310 is performed after the addition of data outputfrom the dynamic OH processing module 152 and the transmission of a datasignal in operations S307 and S308 in the flowchart of FIG. 9. However,in practice, operations S307 and S308 are still being executed whileoperations S309 and S310 are being performed.

As described above, in the transmission apparatus according to the thirdembodiment, it is possible to avoid causing a data signal fail even whena process for statically adding overhead data to a data signal isupdated to a process for adding overhead data corresponding to thespecifications of the data signal to the data signal. That is, it ispossible to execute a specification change of processing of overheadwithout causing a data signal fail.

In addition, the size of circuits in all the overhead processing modulesin the transmission apparatus according to this embodiment can berestricted to be smaller than that of circuits in a transmissionapparatus in which overhead processing modules are fully duplicated.More specifically, the size of circuits according to this embodiment isadvantageously the same as that of circuits for performing normalprocessing of overhead, except for an increase due to the number (x inthis embodiment) of overhead processing modules that are expected to bechanged in the future, the OH function selection module 16, the previousvalue data buffer 142, and each selection module. Therefore, the size ofcircuits in the overhead processing module according to this embodimentcan be restricted to be smaller than that of circuits in overheadprocessing modules that are fully duplicated, as well as fabricationcosts being reduced.

Modification of the Third Embodiment

FIG. 10 is a block diagram of a transmission apparatus according to amodification of the third embodiment. This modification is differentfrom the third embodiment in that an FPGA capable of performing partialconfiguration is used therein.

Because the FPGA capable of performing partial configuration is used asthe first FPGA 1, the first FPGA 1 can have the function of the secondFPGA 2 according to the third embodiment.

In this modification, the update of the overhead function of addingfixed overhead and the update of the overhead function of addingappropriate overhead corresponding to the specifications of a datasignal are the same as in the modification of the first embodiment andthe modification of the second embodiment.

Therefore, a case will be described hereinafter in which a state wherean OH function selection module 16 receives overhead data from thestatic OH processing module 144 through the selection module 141 andadds the overhead data to a data signal is changed to a state where theOH function selection module 16 selects overhead data that is suitablefor the specifications of the data signal and adds the overhead data tothe data signal.

The OH function selection modules 16 each have the selection module 161.

The selection module 161 selects, upon receiving an instruction from theCPU 5, either the selection module 141 in a first OH function module 14or the dynamic OH processing module 156 in a third OH function module 15as the source of overhead data to be added to a data signal.

The OH function selection module 16 adds the overhead data obtained fromthe module selected by the selection module 161 to the data signalincluded in the data signal data IF module 11.

The first OH function modules 14 each have the selection module 141, theprevious value data buffer 142, the update flag register module 143, andthe static OH processing module 144. Here, the static OH processingmodule 144 has the function of the static OH processing module 201 inthe second FPGA 2 according to the third embodiment.

When the static OH processing module 144 has been selected as the sourceof overhead data, the selection module 141 switches the source ofoverhead data to the previous value data buffer 142 upon receiving aswitching instruction from the update flag register module 143. Theselection module 141 then adds overhead data output from the previousvalue data buffer 142 to a data signal included in the data signal IFmodule 11. At this time, the selection module 141 prevents data outputfrom the static OH processing module 144 from overwriting the datasignal.

In addition, when the previous value data buffer 142 has been selectedas the source of overhead data, the selection module 141 switches thesource of overhead data to the static OH processing module 144 uponreceiving a switching instruction from the update flag register module143. The selection module 141 then receives overhead data from thestatic OH processing module 144 and adds the overhead data received fromthe static OH processing module 144 to a data signal included in thedata signal IF module 11.

In the normal operation, the previous value data buffer 142 overwritesoverhead data stored therein with overhead data output from the staticOH processing module 144.

When an update of the static OH processing module 144 is performed, theprevious value data buffer 142 prevents overhead data output from thestatic OH processing module 144 from overwriting overhead data storedtherein upon receiving an instruction for preventing overwriting fromthe update flag register module 143. That is, the previous value databuffer 142 keeps holding the overhead data stored therein. The previousvalue data buffer 142 then outputs the overhead data held thereby to theselection module 141.

Furthermore, when the update of the static OH processing module 144 hasbeen completed, the previous value data buffer 142 resumes overwritingthe overhead data stored therein with overhead data output from thestatic OH processing module 144 upon receiving an instruction forresuming overwriting from the update flag register module 143.

In the normal operation, the update flag register module 143 instructsthe previous value data buffer 142 to perform overwriting the overheaddata output from the static OH processing module 144 until receiving anotice that an update of the static OH processing module 144 will beperformed. Furthermore, in the normal operation, the update flagregister module 143 instructs the selection module 141 to select theoverhead data output from the static OH processing module 144 untilreceiving a notice that an update of the static OH processing module 144will be performed.

Upon receiving a notice that an update of the static OH processingmodule 144 will be performed, the update flag register module 143instructs the previous value data buffer 142 to prevent performingoverwriting the overhead data output from the static OH processingmodule 144. Furthermore, upon receiving the notice that an update of thestatic OH processing module 144 will be performed, the update flagregister module 143 instructs the selection module 141 to select theoverhead data output from the previous value data buffer 142.

Upon receiving a notice that the update of the static OH processingmodule 144 has been completed, the update flag register module 143instructs the previous value data buffer 142 to perform overwriting theoverhead data output from the static OH processing module 144. Inaddition, upon receiving the notice that the update of the static OHprocessing module 144 has been completed, the update flag registermodule 143 instructs the selection module 141 to select the overheaddata output from the static OH processing module 144.

The third OH function modules 15 each have the alarm termination module151, the dynamic OH processing module 152, and the selection module 153,as well as the partial OH function module 154. Furthermore, the partialOH function module 154 has the alarm termination module 155 and thedynamic OH processing module 156.

Since the first FPGA 1 can perform the partial configuration, it ispossible to update only the partial OH function module 154. If an updateof the partial OH function module 154 is performed, the reconfigurationof the partial OH function module 154 is performed by the FPGAconfiguration controller 101 using configuration data, which is storedin the flash ROM 4, for changing the specifications of overhead of thedynamic OH processing module 156 to new specifications. Thus, thespecifications of the dynamic OH processing module 156 are updated.Furthermore, the CPU 5 performs initial setting of the dynamic OHprocessing module 156 using overhead setting data held by the backupmemory 103.

When the initialization has been completed, the alarm termination module155 detects an alarm from a data signal included in the data signal IFmodule 11 and terminates the detected alarm. The alarm terminationmodule 155 then outputs the content of the detected alarm to the dynamicOH processing module 156.

The dynamic OH processing module 156 obtains, from among the multipleoverhead data blocks included therein, overhead data corresponding tothe content of the alarm detected by the alarm termination module 155.

The partial OH function module 154 outputs the overhead data obtained bythe dynamic OH processing module 156 to an OH function selection module16.

As described above, in this modification, it is possible to execute aspecification change of overhead using the partial configurationperformed by an FPGA without causing a data signal fail even in a casein which a state where a fixed value is added is changed to a statewhere appropriate overhead data is selected and added to a data signal.Since the partial configuration is performed, the size of circuits inall the overhead processing modules according to this modification canbe restricted to that of circuits obtained by adding at least oneoverhead processing module to circuits for performing normal processingof overhead. Therefore, the size of circuits can be further reduced.

For example, assume that there is a transmission apparatus in which thenumber of overhead processing modules that add fixed value of overheaddata is 10 and the number of overhead processing modules that addappropriate data in accordance with a data signal is 10. When the sizeof circuits in one overhead processing module is assumed to be 1, a sizeof circuits of 20×2=40 is needed if the overhead processing modules arefully duplicated. On the other hand, because the size of circuitsbecomes 1.2 times as large due to the OH function selection module 16,the previous value data buffer 142, and each selection module, the sizeof circuits in the transmission apparatus according to this modificationis (20+1)×1.2=25.2. Therefore, in this case, the size of circuits in thetransmission apparatus according to this modification can be restrictedto 63% of that of circuits in a transmission apparatus in which a fullyduplicated configuration is adopted.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinventions have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

What is claimed is:
 1. A transmission apparatus comprising: a datasignal processor to add first data of a control signal to a data signalreceived, and transmit the data signal to other transmission apparatus;a first signal output module to output second data of the controlsignal; an update controller to control an update of a function includedin the first signal output module; and a second signal output module,when a notice of an instruction for updating the function included inthe first signal output module from the update controller is received,to output the first data of the control signal that is the second dataof the control signal held in the second signal output module when thenotice of the update instruction is received, wherein the second signaloutput module, when a notice of a completion for updating the functionincluded in the first signal output module from the update controller isreceived, outputs the first data of the control signal that is thesecond data of the control signal received from the first signal outputmodule updated by the update controller.
 2. The transmission apparatusaccording to claim 1, wherein: the second signal output module includesa data storage module for storing the second data of the control signal;the first signal output module outputs the second data of the controlsignal for being stored in the data storage module; the updatecontroller controls an update of the second data of the control signalstored in the data storage module; when the notice of the instructionfor updating the function included in the first signal output modulefrom the update controller is received, the update controller controlsthe data storage module to stop updating the second data of the controlsignal, and the second signal output module outputs the first data ofthe control signal that is stored in the data storage module; and whenthe notice of the completion for updating the function included in thefirst signal output module from the update controller is received, theupdate controller controls the data storage module to resume updatingthe second data of the control signal, and the second signal outputmodule outputs the first data of the control signal that is stored inthe data storage module.
 3. The transmission apparatus according toclaim 1, wherein: the first signal output module outputs the second dataof the control signal based on alarm included in the data signal; thesecond signal output module, when the notice of the instruction forupdating the function included in the first signal output module fromthe update controller is received, outputs the first data of the controlsignal based on the alarm included in the data signal that is data ofthe control signal based on the alarm included in the data signalgenerated in the second signal output module; and the second signaloutput module, when the notice of the completion for updating thefunction included in the first signal output module from the updatecontroller is received, outputs the first data of the control signalthat is received from the first signal output module updated by theupdate controller.
 4. The transmission apparatus according to claim 3,wherein: the second signal output module includes a data storage modulefor storing the second data of the control signal; the first signaloutput module outputs the second data of the control signal for beingstored in the data storage module; the update controller controls anupdate of the second data of the control signal stored in the datastorage module; when the notice of the instruction for updating thefunction included in the first signal output module from the updatecontroller is received, the update controller controls the data storagemodule to stop updating the second data of the control signal, and thesecond signal output module outputs the first data of the control signalthat is stored in the data storage module; and when the notice of thecompletion for updating the function included in the first signal outputmodule from the update controller is received, the update controllercontrols the data storage module to resume updating the second data ofthe control signal, and the second signal output module outputs thefirst data of the control signal that is stored in the data storagemodule.
 5. The transmission apparatus according to claim 1, wherein thefirst signal output module and the second signal output module areimplemented on an FPGA (Field Programmable Gate Array) capable ofperforming partial configuration.
 6. The transmission apparatusaccording to claim 1, further comprising: a fixed signal output moduleto output the data of the control signal processed by a function thatthe update is unnecessary.
 7. A transmission apparatus, comprising: aprocessor configured to execute a procedure, the procedure comprising:receiving a data signal; updating a function included in a module; whena notice of an instruction for updating the function included in themodule is received, outputting data of a control signal that is held inthe module when the notice of the update instruction is received, andtransmitting the data signal to which the held data of the controlsignal is added to other transmission apparatus; and when a notice of acompletion for updating the function included in the module is received,outputting data of the control signal from the updated module, andtransmitting the data signal to which the data of the control signal isadded to other transmission apparatus.
 8. A method for controlling atransmission apparatus, comprising: receiving a data signal; updating afunction included in a module; when a notice of an instruction forupdating the function included in the module is received, outputtingdata of a control signal that is held in the module when the notice ofthe update instruction is received, and transmitting the data signal towhich the held data of the control signal is added to other transmissionapparatus; and when a notice of a completion for updating the functionincluded in the module is received, outputting data of the controlsignal from the updated module, and transmitting the data signal towhich the data of the control signal is added to other transmissionapparatus, executed by a processor.